template<typename T, int size>
struct base_vec
{
    T v[size];
 
    virtual T getLength()
    {
        return 1;
    }
 
    virtual ~base_vec(){}
};
 
template<typename T, int size>
struct vec : public base_vec<T, size> ///Das Klassentemplate
{
};
 
template<typename T>
struct vec<T, 3> : public base_vec<T, 1> ///Spezialisierung
{
    vec(){}
    vec(T , T, T){}
};
 
typedef vec<float, 2> vec2f;
typedef vec<float, 3> vec3f;
typedef vec<float, 4> vec4f;
 
int main()
{
        vec3f f(1, 2, 3);
        f.getLength();
}
 

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